Here are some of the key languages used:
* English: The primary language of the Allied forces, especially the United States and Great Britain.
* German: The language of the Axis powers, primarily Nazi Germany.
* Japanese: The language of the Empire of Japan, another Axis power.
* French: Spoken by the French Resistance and the Free French Forces.
* Russian: The language of the Soviet Union, a major Allied power.
* Italian: Spoken by both the Italian Fascist regime and the Italian Resistance.
It's important to remember that soldiers and civilians from numerous other countries participated in the war, and many different languages were spoken on the battlefields and in the home fronts.